Does Brazilian Jujitsu teach defense against weapons?

BJJ is descendant of Judo, not Jujutsu. There's a big difference.

It's rare and usually from the Helio/Rorion line of BJJ, but yes, it is taught. It's even required for advancement in some schools, including one I've attended. They're basically traditional Japanese Jujitsu defenses ending in arm locks against the shoulder, elbow, or wrist, or a throw with a finishing strike or two. You can find many of them in Royce Gracie's self-defense book. I believe Modern Army Combatives has also adapted their weapons defense from the Gracie program.

None at the moment. The sport BJJ you see is pure unarmed hand-to-hand. There is no weapons component in sport BJJ. However, the combatives program of Gracie Jiu-Jitsu does address some defense against weapons, namely taken from its predecessor Judo.

Any outstretched arm or leg is vulnerable to a lot of jujutsu techniques. That goes for anything that is used to strike a vulnerable area too. The assumption with several moves is that the opponent will not be able to generate enough power to strike effectively because of being in an awkward position.

If you look beyond the sport aspect of martial arts, you will find that almost all martial arts have effective self defense including defense against weapons. BJJ is no exception.

It depends on the Instructor if its the Gracies especially Rorion and Royce Yes but most schools nowadays no its mostly catered to competition of either GI or No-Gi or MMA.

My friend. If i were u i'd go for Aikido classes or Ninjutsu

Aikido is an awesome styl by protecting ur self and ur enemy from injury not pain but injury.

Ninjutsu is a vast martial art from weapon training to koshijutsu(attack against muscle and nerve points) and all in between.

Ninjutsu counter is really good for defence and making ur enemy look stupid

so please type this on the google search tab: Ali Abdul Karim

his a ninjutsu master and he'll show u how awesome it is

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The stand-up techniques in Gracie Jiu Jitsu are largely from Japanese Jujutsu (knife defence, gun defence, throws, blocking, striking etc.) so in that sense yes it will

Not typically.

BJJ is not designed for that.